Young Investigator Award. Percutaneous facet joint fusion: preliminary experience

The synovium-lined apophysial joint is an important cause of back pain through facet arthrosis and nerve root pressure. The short-term results of two relatively noninvasive treatments--facet block and facet rhizotomy--have been better than their long-term results. The authors propose treatment with fusion of the posterior facet joints in the lumbar spine by means of a simple percutaneous procedure performed under local anesthetic with use of radiologic guidance.

In the first phase of this study the technical feasibility of the concept was established in human cadaver spine. In the second phase a canine model was tested in which bone grafts were surgically inserted into lumbar facet joints. Five male and two female mongrel dogs, weighing 18-25 kg (mean, 20.3 kg), were operated on. Each procedure was done in three steps: First, preoperative computed tomographic (CT) scans were obtained to measure facet depth. Second, surgery was performed under fluoroscopic guidance with use of a threaded guide wire, a small cannulated coaxial drilling system, and hydroxyapatite cancellous bone plugs. Third, early postoperative CT scans were obtained to verify bone plug location. CT was repeated at 4 and 6 months after surgery to check for fusion. The dogs were killed at 6 months, and histologic examination was performed.

Successful insertion of the bone plug was achieved in 12 of the 14 facets (86%). One dog died as a complication of the procedure. Fusion occurred in five of the 12 surgically treated facets (42%).

Drilling and surgical insertion of bone plugs into facet joints of dogs were feasible. The fusion results are promising and may improve with future modifications of the technique.